A 52-page report by the House of Commons public accounts committee published on Thursday said whistleblowers were responsible for exposing staff shortages at the service last year. MPs said Serco staff were bullied after they revealed that the company ‘lied about its performance data’ on 252 occasions.

The PAC report said NHS Cornwall and Isles of Scilly was ‘deeply ineffective’ and ‘made some bonus payments despite the fact that Serco’s performance was falling well short of what was required’.

‘Even when it knew that Serco had falsified performance data, the PCT did not fine the contractor or terminate the contract,’ the report said.

Committee chairwoman Margaret Hodge (Lab, Barking) said: ‘It is disgraceful that the public had to rely on whistleblowers to find out that the out-of-hours GP service in Cornwall, provided by private contractor Serco, was short-staffed and substandard, and that service data was being manipulated, making the company’s performance look better than it was.

'The failures in this contract matter, because the NHS will be making increasing use of private and voluntary providers to deliver NHS services. We must have confidence in the ability of NHS commissioners to contract effectively, to monitor rigorously, and to extract appropriate penalties and where necessary terminate contracts. None of these conditions were met in Cornwall.’

The PAC report urged NHS England to give clear guidance and prompt advice to CCGs about whether services should be put out to tender, and warned the NHS needs to be ‘commercially shrewd’ in dealing with major contractors so that ‘contracts have the right framework and obligations and that performance is rigorously scrutinised’.

MPs said NHS England should require CCGs to publish data in a common format, showing local performance against national quality requirements. NHS England should also seek assurance from all NHS 111 service providers, the MPs said, that they 'have sufficient staff in place, and that they have contingency plans’.

Director of Serco’s out-of-hours service in Cornwall, Dr Louis Warren, said: ‘It’s really important that the local people in Cornwall do not lose confidence in this essential urgent care service; it is a valued part of the local NHS and we are proud of our professional team who provide it. The evidence to the PAC confirms that it is one of the best performing GP out-of-hours services in the country.

‘The PAC hearing and report refers to a number of issues that we faced last year. When we discovered these problems we took swift and decisive action to put the situation right and apologised to the people of Cornwall.

‘The health regulator, the CQC, has said that we have met all standards including staffing levels following its unannounced visit last month. The service delivers a high standard against the national quality requirements and patients and users of the service over the past two years consistently give the service a satisfaction rating of 95% or higher.’